Method and device for antiaircraft firing



Feb. 9, 1932. Y. M. P. (5. LE PRIEUR ET AL 138441429 METHOD AND DEVICEFOR ANTIAIRCRAFT FIRING Filed July '7, 1930 4 Sheets-Sheet l Flg- 2 Iens? 1' a. IZVJ Feb. 9, 1932.

Y. M. P. G. LE PRIEUR ET AL METHOD AND DEVICE FOR ANTIAIRCRAFT FIRINGFiled July 7, 1930 4 Sheets-Sheet 2 van o R3 Feb. 9, 19 32. Y.YM. P. G.LE PRIEUR Ef AL 1,844,429

METHOD AND DEVICE FOR ANTIAIRCRAFT FIRING Filed July '7, 1930 4Sheets-Sheet 3 Feb. 9, 1932. Y. M. P. G. LE PRIEUR ET AL ,8

METHOD AND DEVICE FOR ANTIAIRCRAFT FIRING Filed Jilly 7, 1930 4Sheets-Sheet 4 Fig; [I

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YVES MARIE PAUL GASTON LE PRIEUR AND AUGUSTE LDUIS RECORDED, OF PARIS,

FRAQBFCE, :ASSIGNOR8 T PRECISION MODERNE, 0F PARIS,

OF FRAIIQE (7E, A GQBPORATION METHOD AND DEVICE FOR ANTIAIEGRAFT FIEIEGApplication filed July 7, 1830, Serial No. 466,272, and. in France July9, 1929.

The present invention has for its object a line of sight foranti-aircraft guns such as machine guns and ordnance firing from ground.

Generally speaking, such lines of sight or correcting devices allow whena field glass or the like is directed towards the aircraft to give thisfield glass or the gun or a part parallel thereto the angular correctionrequired is for the projectile to hit the point in space tile thecorrection in the range as measured by the teleineter during the time offlight, which range is increased or not by a complementary amountaccording as to whether it is desired tofire on the target itself and toaim continuously at it or to produce in front of it a curtain fire whichit would have to pass through during the volley if it were to continuemoving in-the same direction.

The geometrical constructions and the calculations used according to themethod which is the object of the present invention will first'bedisclosed with reference to Figs.

1 to 7 of accompanying drawings, said method being practically executedin the apparatuses to be described later.

Figs. 1, 2, 3., d concern the corrections due to the movement of thetarget and the deforto mation of the projectile path.

Figs. 5 to 7 relate to the wind correction Fig. 8 is a geometricalfigure allowing the principle of the apparatus to be better understood.

Fig. 9 is aside view showing the arrangment on a gun-carriage of thediflerent parts of the correcting devlce.

Figs. 10 and 11 are simplified vertical crosssections perpendicular toeach other of the correcting device, the part pertaining to the windcorrection being removed for sake of simplicity.

t Fig. 12 is a plan view of this part of the correcting dev ce whichprovides this wind correction.

In the first place, referring to Figs. 1 to 4, A, is the position of themoving target termed hereinafter the aircraft at the moment of thefiring of a round by the gun O. A is its location at the moment where itis met by the projectile, this is the futuretarget.

Supposing 2? is the time of flight of the pro'ectile.

the speed of the aircraft.

D the distance to the position of the target at the start.

lhe vector A,A is equal to Vt.

0B =1) is the length comprised between the trunnion of the gun and thevertical of point A, the length of this vertical AB being 10corresponding to the lowering of the tra ectory.

The method consists chiefly in reproducing homothetically at reducedscale the polygon U AQAB with a suitable reduction scale.

Fig. 2 shows the figure in space 0A AB, reduced at the scale 1 /L inwhich case Vt (2) a u= he (3) all- The calculating device will form thisre duced pol gon, this is made easier by admitting p .(L) which isperfectly true in till vacuo and sufficiently approximating truth Iunder normal firing conditions.

The formula (2) gives the correction of displacement of the targetduring the time of flight t.- In View of making the operation automaticand of reducing the number of at tendants, it has been admitted alsothat i=6 (L) which is also perfectly true in vacuo.

onsequently p=f(t) or It is thus apparent that the distance D,

at the time of firing being known, the application of the formulae (1),(2) (3) and (5) allows the automatic introduction of the values of p andt corresponding to the future distance without any other reading to bemade beyond that of the distance D Turning now to- Figs. 3 and lshowingv means for obtaining a complementary time interval for quickfiring from a machine-gun or quick-firing ordnance the complementarytime 0 is equal to half the duration of the firing of the gun and isadded to the duration of travel so as to fire at a pfoiut in front ofthe position by the amount The correction due to the displacement of theaircraft is calculated during the time t+e.

The correcting device will practically give body to Fig. 3 wherein:

Supposing short outbursts of fire are provided at small distances andlong outbursts at large distances, experience shows it is possible towrite:

K being a suitable constant.

It should he noted that instead of the scale adapted in Figs. 2 and 3for reducing the polygon 0A AB, it is possible to use the scale of Fig.4. For small distances a simple linear formula binds the amounts t-i-et+e Referring now to Figs. 5 to 7, supposing W is the speed of thehorizontal wind; the aircraft is carried by it from A to A through adistance Wt to be geometrically added to the vector Vt.

To reach the point A it is necessary on account of the action of thewind on the projectile to direct the gun not'towards A but towards A A Abeing disposed against the direction of the wind and equal to K'wt;

A A =KWt against the direction ofthe wind.

In the first case the correcting'device will form at the scale '(Fig. 6)the triangle oA A which" becomes ()aa wherein a -g wu-Kg.

in the second case the triangle OA A becomes Oa a (Fig. 7 wherein KWt LA form of execution of the apparatus for executing the method accordingto the invention has been shown by way of example in Figs. 8 to 11.

Fig. 8 shows means for executing the polygon of Fig. 2; the direction ofthe vector parallel to the path of the target is obtained by means of ahorizontaland of a vertical plate connected in a manner such that asingle operation allows the two following rotary movements to beperformed:

(a) A rotation round the vertical axis yy' with a view to laying theangle between the azimuth of the gun and the horizontal projection ofthe path of the aircraft;

(1)) A rotation in the vertical plane 3 dy' containing this projectionofthe path of the aircraft with a view to laying down the angle d a d ofthe aircraft with the horizontal.

On the line thus obtained am a length aa is borne which is equal to Thearrangement of the two plates is then submitted to a vertical movement Iand These difierent amounts are formed mechanically by the devices shownin Figs. 9 to 11.

A frame 1 is automatically held vertical through the agency of aparallel motion comprising a stationary arm 2 forming an extension ofthe gun carriage head, a sight-bar 3 parallel to the axis of the gun anda con-- necting rod 4 integral with the frame 1, the fourth side beingformed by the gun on the cradle of which is provided a pivot 5 for theconnecting rod. 1

The frame 1 carries on its outer side a slide 6 wherein moves a slider 7ending at its upper end with a horizontal circular plate wherein thesunwheel 9 carrying at its upper part a rose 10 is adapted to rotate.

A pinion 11 meshes with the wheel 9. It receives its movement from asliding Cardanshaft 12 the other end of which carries a pinion 13meshing with a stationary circular rack 14.

The gear ratio is such that the sunwheel 9 remains angularly stationaryin space during all the azimuthal rotations of the gun carriage.

A target plate 16 adapted to rotate with reference to the plate 8 andthe sun-wheel 9 is provided with a pointer 17. The radius leading to thepointer shows the intersection with the horizontal plane of the verticalplane passing through the aircraft. The number read in front of thepointer 17 shows the direction of the aircraft, If the aircraft does notchange its path, the pointer 17 gives out the same division of the roseduring the entire revolution of the gun-carriage.

A rose or more correctly compass card is a horizontal circular member ordisk graduated in degrees or the like starting from a predeterminedorigin and one findsones position in space in such a manner that themeridian plane (plane of the origin) of the rose assing through thisorigin, also passes throug the geographical north or another knowncardinal point. The point of origin of the graduations bears thereference North or N. The diametricallyop osed point bears the referenceSouth or S etc. The plate 16 is provided with pistons 18 which engage aninner toothwork of the wheel 9 whereby the plate is driven by the wheelafter the plate has been given the desired angular starting position.

An arrow-shaped bar 19 serves to make the target plate 16 rotateaccording to the direction of movement of the aircraft when the latterchanges its path. This bar is held as well known in gunnery parallel tothe frame of the aircraft or to its path.

It may rock in the vertical plane so as to be parallel in space .to theframe of the aircraft even if the flight is not horizontal.

This control of the bar, in the vertical direction has for its result aninstantaneous correction of the speed of the aircraft so as to take intoaccount the action on it of a downward or upward direction of theaircraft.

It is known in effect that the speed of a downwardly moving aircraftincreases and that of an upwardly moving aircraft is reduced. Thisresult is accomplished as follows:

A circular vertical plate20 rigidly secured to the directing bar 19,rotates with friction inside a circular recess of the object plate 16.

' Its axis of rotation is horizontal and crosses the vertical axis ofthe plate 16. A slider 21 passes through a guide in the plate 20 formedalong a diameter parallel to the directing bar.

The slider 21 is provided-with two knobs or projections of-which one 22engages an aperture in the vertical rod 23 ending with a rotula34corresponding to the point (t of Figs. 2 and 8; the other knob 24engages the groove of a cam 25 disposed behind the plate.

The working of this arrangement is as follows (a) Any rotation 'of thecam 25 causes an advance motion of the knob Y24: and consequently of theslider 21 in its groove which provides a varying eccentricity of theknob 22 and consequently of the rod 23;

(b) Any downward or upward movement of the aircraft corresponding to anobli uity of the slider in the guiding groove of plate 20 has as aconsequence a displacement of the slider 21 under the action of the knobthe 24amoving in the groove of the cam stationary at the momentconsidered.

The curve chosen should be such as will prevent any jamming betweenmechanical parts. It depends on one hand, as stated, on the law supposedto govern the modifications of speed during sloping flight and on theother hand on the mannerv in which is calculated the correction due to,the displacement of the aircraft. The cam serves together for thecontrol of the eccentricity corresponding to the slope and of thatcorresponding to horizontal speed of the aircraft.

The preferred urveis a logarithmic spiral which has as an advantage theprovision of a constant engagement angle between the cam and thecorresponding projection. 'This spiral is suitably chosen so as toreproduce as far as possible the normal variation in speed of theaircraft the path of which is not horizontal.

This logarithmic spiral afiords means for giving the rod 23 aneccentricity corresponding to the horizontal displacement of theaircraft.

As illustrated in Fig. 2 this eccentricity should be This means logr=log=1b V+log As the cam spiral is logarithmic, it is neces-v sary to impartto it the sum of twolrotations proportional respectively to log V and tolog The cam is cut in a circular roller 25' outwardly toothed andmeshing with a Worm 26 controlled by the planet wheel of a differential27 the frame of which is under the control of a'pinion keyed tothe shaftof a handle 28 adapted to move in front of a logarithmic scale ofspeeds.- The other planet wheel re-v ceives, as will be explainedhereinafter, a rotation proportional to v i L To the so-called rotula.or universal joint 34 is pivotally secured the end of the rod 41 slidingin the sleeve 42 fitting in its turn in the socket of the cardan shaft43 the horizontal axis of which is at a distance from the axis 40 equalto the length considered as the unit in the device so as to correspondto line 0?) in Fig. 2. V

Obviously the distance along rod 41 between the rotula 34' andthe axis44 varies proportionally to and corresponds to the distance Oa of Fig.2.

On the other hand it is obvious that to each value of D and ofcorresponds only on value of L and consequently of as it has beensupposed that t=f(L'). If

and D are suitably combined, it is therefore possible to obtain and totransmit it to the differential 27.

. To this end the variations of are transmitted through a flexible shaft30- of the Bowden type secured to the end of the rod,41 and the sheathof which bears against the sleeve 42, to a hand 31 moving over a discshaped abacus 32 provided with curves corresponding to the differentdistances D This disc-shaped abacus is rotated th'rc'iugha worm and agear train by a shaft 33 provided with a handwheel. This shaft controlsthrough bevel pinions the rotation of the rod 38 carrying the abovementioned planet wheel of the differential 27.

The eccentricity of the projection 22 is thus caused to be proportionalto -This is obtained by giving the'slider 7 the said motion.

The amount may be obtained through an abacus giving out the curvesdepending on the distances and the angles of sight.

In the case of thefiring of a machinegun, it may be admitted asexplained hereinabove that is approximately equal to This allows tocontrol the desired vertical motion through the shaft 33 the rotation ofwhich is proportional to The mechanical device described hereinafter isbased on this method.

is adapted to raise the roller 37 on the slider 7. The movement of thecam is obtained through a Wheel 38 meshing with the worm 39 driven fromthe shaft 33-through bevel pinions. The target plate is thus caused torise through a distance Consequently for a speed zero, the rotula 34 isat the intersection of the vertical axis of the plate 16 and of thehorizontal axis of the shaft 40. For any value given to the speed and tothe range, the rotula 34 will be at the point given by the compositionof the vectors as shown in Fig. 2.

The working of the apparatus is as follows:

The attendant begins by directing the arrow 19 parallel to the directionof the aircraft either by sight if no measuring means are at hand, orafter reading on the rose 10 if the angle of the aircraft path may begiven to him. The speed is then registered by bringing the handle 28 infront of thesuitable scale, and the distance is similarly registered byacting on the handwheel of the shaft 33 until the hand 31 arrives on thecurve of the abacus 32 corresponding to the desired distance. Thisprovides in the diflerential 27 the product and causes the cam 25 torotate through a suitable angle through the agency of the worm26. Thedesired eccentricit of the rotula 34 is thus obtained and the slghtglassis given the required correction. The layer has now only to return thesightglass on to the aircraft through the laying handwheels of thegun-carriage and to keep it directed on to said aircraft,

If it is desired to fire by outbursts, the above mentioned formula t+e Tbeing used, the apparatus may be simplified. In this case 4 V6 e) Lbecomes VK and the differential 27 may be done away with. The scale overwhich moves the handle 28 gives out the logarithms of VK and the shaft33 provides simply the vertical motion When it is desired to provide thewind corrections by means of the apparatus described (Fig. 12), thesunwheel9 driven by the pinion 11 so as to remain stationary in space Iduring the rotation of the gun-carriage, in-

stead of having as in the case of Figs. 10 and 11, a circular borewherein the plate 16 is adapted to rotate,'contains a plate 51frictionally held in said sunwheel 9. This plate has a slideway 52 forthe slider 53 carrying the plate 16 with the correcting parts such asthe plate 20, the arrow 19 and the like.

The apparatus is made use of as follows: Supposin the zero of the scaleof the sunwheel 9 is directed towards the north and is held thus throughthe rotation of the pinion 11, the slideway 52 is given a directionparallel to that of the wind by bringing for in- I stance ahand integralwith this slider way in front of the desired graduation of the sunwheel9. ,On the other hand, the speed of the wind is registered by moving theslidin a system of predetermined coordinates, for determining a functiongraphically assuming, for exam le, that one has to determine a function2= (:1: y) this equation could be determined by tracing in a system ofrectangular coordinates ow,0y,the curves z=a, z= b, z=c, etc. If it isdesired to have the value of a corresponding to ma, 3/0, it will besufiicient to find the posltion of the point M (m0, 3 0) relative to theabove curves.

What we claim is:

1. An apparatus for the correction of antiaircraft gun firing comprisingtwo arms pivotally secured to each other one of which of constant lengthis parallel to the gun, a sight glass carried by the other arm and meansfor giving the outer end-of said other arm a movement parallel to themovement of the object and equal to the pathcovered by it during apredetermined time at the desired scale and a vertical motion equal tothe loss 1 of height of the projectile passing throu h the end of saidpath with reference to the axis of the gun at the same scale.

2. An apparatus for-the correction of antiaircraft gun firing comprisingtwo arms pivotally secured to each other one of which of constant lengthis parallel to the gun, a sight glass carried by the other arm, avertical rod ivotally secured to the outerend of the said other arm, ahorizontal rotary plate, means for radially guiding the vertical rod insaid plate, means for constraining said guiding means to remain parallelto the projection of the direction of motion of the target, means forcausing the distance between the vertical rod and the center of theplate tobe equal to the path covered by the target during the time'offlight at a scale of L being the distance measured along the axis of thegun between the gun and the vertical passing through the end of the pathtraveled by the target during the flight of the projectile and means formoving vertically the plate by an amount equal to the loss of height ofthe projectile passing through the end of said path with referenceto'the axis of the gun at the same scale as above.

3. An apparatus for the correction of antiaircraft firing comprising twoarms pivotal- 1y secured to each other one of which of constant lengthis parallel to the gun, a sight glass carried by the other arm, avertical rod pivotally secured to the outer end of said other arm, ahorizontal rotary plate, means for radially guiding the verticalrod insaid plate means for constraining said guiding means to remain parallelto the projection of the direction of motion of the target, means forcausing the distance between the vertical rod and the. center of theplate to be equal to the path covered by the target during the time offlight at a scale of L being the distance measured along the axis of thegun between the gun and the vertical passing through the end of the pathtraveled y the target during the flight of the projectile, a spirallygrooved vertical cam, a part engaging same and controlling thetransverse movements of the rod, means for keeping the cam parallel tothe displacement of the target, means for rotating same and means fordisplacing the plate vertically by an amount equal to the loss of heightof the projectile passing through the end of said path with reference tothe axis of the gun at the same scale as above. v

4-. In an apparatus as claimed in claim 3 a slider pivotally secured tothe rod, a vertical plate parallel to the cam along a diameter of whichthe slider is adapted to move and means for keeping the said diameterparallel to the path of the target.

5. An apparatus for the correction of antiaircraft firing comprising twoarms pivotally secured to each other one of which of constant length isparallel to the gun, a sight glass carried by the other arm, a verticalrod pivotally secured to the outer end of said other arm, a horizontalrotary plate, means for radially guiding the vertical rod in said plate,means for constraining said guiding means to remain parallel to theprojection of the direction of motion of the target, means for causingthe distance between the vertical rod and the center of the plate to beequal to the path covered by the target during the time of flight at ascale of ,the target, an adding differential gear controlling therotation of the cam and separate means for giving said gear elementaryrotations equal to log V and log V being the speed of the aircraft and tthe time of flight, and means for displacing the plate vertically by anamount equal to the loss of height of the projectile passing through theend of said path with reference to the axis of the gun at the same scaleas above.

6. An apparatus for the correction of antiaircraft firing comprising twoarms pivotally secured to each other one of which of constant length isparallel to the gun, a sight glass carried by the other arm, a verticalrod pivotally secured to the outer end of said other arm, a horizontalrotary plate, means for radially guiding the vertical rod in said plate,means for constraining said guiding means to remain parallel to theprojection of the direction of motion of the target, means for causingthe distance between the vertical rod and the center of the plate to beequal to the path covered by the target during the time of flight at ascale of L being the distance measured along the axis of the gun betweenthe gun and the vertical passingthrough the end of the path traveled bythe target during the flight of the pro ectile, a spirally groovedvertical cam, a part and means for displacing the plate vertically by anamount equal to the loss of height of the projectile passing through theend of said path with reference to the axis of the gun at the same scaleas above.

7. An apparatus for the correction of antiaircraft firing comprising twoarms pivotally secured to each other one of which of constant length isparallel to the gun, a sight glass carried by the other arm, a verticalrod pivotally secured to the outer end of said other arm, a horizontalrotary plate, means for radially guiding the vertical rod in said plate,means for constraining said guiding means to remain parallel to theprojectionof the direction of motion of the target, means for causingthe distance between the vertical rod and the center of the plate to beequal to the path covered by the target during the time of flight at ascale of L being the distance measured along the axis of the gun betweenthe gun and the vertical passing through the end of the path traveled bythe target during the flight of the projectile, a spirally groovedvertical cam, a part engaging same and controlling the transversemovements of the rod, means for keeping the cam parallel to thedisplacement of the target, an adding gear controlling the rotation ofthe cam, means for giving said gear an elementary rotation equal to log.V, a plate graduated in distances, common means cooperating therewithfor giving the gear a second elementary rotation equal to log and fordisplacing the plate vertically by an amount equal to the loss of heightof the projectile passing through the end of said path with reference tothe axis of the gun at the same scale as above.

8. An apparatus for the correction of antiaircraft firing comprising twoarms pivotally securedto each other one of which of constant length isparallel to the gun, a sight glass carried by the other arm, a verticalrod pivotally secured to the outer end of said other arm, a horizontalrotary plate, means for radially guiding the vertical rod in said plate,means forconstraining said guiding means to remain parallel to theprojection of the direction of motion of the target, means for causingthe distance between the vertical rod and the center of the plate to beequal to the path covered by the target during the time of flight at ascale of L being the distance measured along the axis tures.

passing through the endof the path traveled by the target during theflight of the projectile, a spirally grooved vertical cam, a partengaging same and controlling the transverse movements of the rod, meansfor keeping the cam parallel to the displacement of the target, anadding gear contrplling the rotation of the cam, means for giving saidgear an elementary rotation equal to log. V, a plate graduated indistance, means cooperating therewith for giving the gear a secondelementary rotation equal to log a cam controlled by last mentionedmeans for displacing the plate vertically by an amount equal to the lossof height of the projectile passing through the end of said path withtioh in space and comprising a sunwheel,

spring urged pistons making same integral with the plate and a geartrain connecting same with the gun-carriage.

11. In an apparatus as claimed in claim 3, means for correcting theaction of the wind comprising a slider carrying the plate and means formoving said slider in accordance with the wind direction and speed.

In testimony whereof we aflix-our signa- YVES MARIE PAUL GASTOIQ LEPRIEUR. AUGUSTE LOUIS RICORDEL.

